Inositol Phosphatide Research Articles

Phospholipid composition of bile and blood in rats under correction of experimental fatty hepatosis

To date, the aetiology and molecular mechanisms of the development of fatty hepatosis, which is quite common in mammals, have not yet been sufficiently explained. This pathology requires detailed study not only because of functional disorders of the liver and biliary system, but also because of the high probability of dangerous complications – fibrosis, cirrhosis, or hepatocellular carcinoma. The purpose of this study was to determine marker changes in the phospholipid composition of bile and blood in rats with experimental fatty hepatosis and with the use of corrective therapy. Hepatopathology was modelled in Wistar laboratory rats by intragastric administration of a 4% solution of tetracycline hydrochloride at the rate of 0.25 g/kg body weight for seven days. Using the method of thin-layer chromatography, the phospholipid components of animal bile and blood were studied. It was found that during experimental fatty hepatosis in rats, there was a decrease in the total phospholipid content in bile, mainly due to a decrease in the level of phosphatidylcholine (by 22.4-27.0%), the total fraction of inositol phosphatide and phosphatidylinositol (by 20.0-27.3%), and phosphatidylethanolamine (by 17.5-25.2%). Conversely, the introduction of milk phospholipids in the form of a dietary supplement “FLP-MD” in sick animals contributed to an increase in bile levels of phosphatidylserine by 67.1-99.8%, inositol phosphatide and phosphatidylinositol by 48.6-57.6%, phosphatidylcholine by 38.8-60.2%, phosphatidylethanolamine by 45.6-57.4%, and sphingomyelin by 30.4-46.3%. In the blood of such rats, a significant decrease in the content of phosphatidylcholine, phosphatidylserine, and sphingomyelin was found, which was not observed after administration of the “FLP-MD” dietary supplement to sick animals. In the case of using the supplement in healthy animals, only a 29.3% increase in the blood content of inositol phosphatide and phosphatidylinositol was noted. The determination of the most sensitive indicators in the phospholipid spectrum of blood and bile reveals the features of changes in molecular processes for the development of fatty hepatosis in animals, and also contributes to preclinical tests of the corrective effectiveness of newly created drugs according to established markers

KL 16 Abnormal glucose signaling in trophoblast biology

Human trophoblast shows a peculiar carbohydrate metabolism during pregnancy with adaptive responses to systemic alterations that may occur during gestation. In fact, cells may adapt their metabolism to environmental changes driven by inflammatory cytokines, available nutrients and oxygen tension. An interesting adaptation of intracellular signaling occur in human trophoblast under healthy conditions throughout the pregnancy and in case of superimposed complications that alter the surrounding milieu. These modifications are not only passive responses but they may be considered as an active interaction and may be transferred to the mother through specific mediators as an attempt to modulate the maternal systemic reaction. In early gestation, trophoblast invades the endometrium (implantation) and gland secretions represent the initial form of nutrition for the conceptus (histiotrophic nutrition) prior to the complete development of the placenta. An alternative carbohydrate metabolism takes place in this setting that is characterized by low-oxygen tension, lipid and glycolipid secretion that represent the available nutrients, and high concentration of regulatory cytokines due to the immune system activation (fetal-placental interface). Inositol second messengers mediate this metabolic process of glucose non-oxidative use and storage and lipogenesis. Inositol phosphatides were shown to interact with leucocytes at membrane and intracellular level with a sort of reciprocal benefit during those weeks of rapid changes. Inositol phosphoglycans start to leak into maternal circulation to modulate physiological insulin resistance that occurs during healthy pregnancy. When an excessive systemic inflammation occurs like in preeclampsia, the fetal/placental unit pour out large amounts of D-chiro inositol mediators (IPG-P) into maternal circulation being favored by a more permissive placental membrane that show thinner glycocalyx and less tight junctions. These mediators were also shown to play a role in endothelial dysfunction, predisposition to seizures (eclampsia), and cardiovascular disease later in life.

Participation of the inositol phospholipid signaling pathway in the increase in cytosolic calcium induced by tributyltin chloride intoxication of chlorophyllous protozoa Euglena gracilis Z and its achlorophyllous mutant SM-ZK

Exposure of tri- n-butyl tin chloride (TBTCl) as a stressor to Euglena gracilis Z causes rapid alteration of cell morphology followed by deflagellation. The present study was undertaken to reveal the mechanism of the cell response at a molecular level. Chlamydomonas reinhardtii, in this study E. gracilis Z and its achlorophyllous mutant SM-ZK, gave similar results when subject to the same stressor. Indeed, similar results were obtained with both strains. Next, assuming that the morphological alteration caused by TBTCl is mediated by the inositide phosphate-lipid signaling pathway, the effects of signal transduction and Ca 2+ release reagents (mastoparan as a G-protein activator, neomycin as a phospholipase C inhibitor, verapamil as a Ca 2+ channel blocker, and A23187 as a Ca 2+ ionophore) on morphology and intracellular Ca 2+ levels were examined with or without TBTCl. The data strongly suggest that the morphological alteration is mediated by an increase in Ca 2+ linked to the inositol phosphatide pathway. The cellular response to signal transduction inducing reagents was compared between the E. gracilis chlorophyllous Z strain and its achlorophyllous mutant SM-ZK strain. Significant differences were observed between the Z and SM-ZK strains in terms of the stress response and intracellular Ca 2+ level.

Role of Membrane Lipids in Powdery Mildew Infection of Cucumber

Since altered partitioning of photosynthate into lipids of cucumber leaf tissue, particularly increased synthesis of PI, during infection by Sphaerotheca fuliginea , the reversal of such changes in the presence of lithium chloride, pointed to the possible stimulation of the inositol phosphatide cycle in the hostpathogen interaction, further evidence was sought in this limited study of myo-[2- 3 H]inositol incorporation by healthy and infected leaves. Compared with healthy tissue, infected leaf tissue showed increased labelling of inositol phosphatides IP 1–3 , during a 36h chase period. This finding is consistent with the hypothesis that the reduction in powdery mildew disease, observed in cucumber plants supplied systemically with lithium chloride (Abood et al., 1991) could be due to interference with phosphatidyl inositol turnover.

Rapid and sensitive anion-exchange high-performance liquid chromatographic determination of radiolabeled inositol phosphates and inositol trisphosphate isomers in cellular systems

A rapid and sensitive high-performance liquid chromatographic method for the determination of multiple inositol phosphates and inositol trisphosphate isomers was developed. The separation of inositol phosphates was optimized by controlling the ionic strength with stepped gradient programs and the pH of mobile phase. Six inositol phosphates were determined within 22 min or the six compounds plus an inositol trisphosphate isomer within 24 min using a single anion-exchange column containing the quaternary ammonium functional group. This technique was successfully applied to the determination of inositol phosphatide turnover by AIF 4 − stimulation in a small amount (5 · 10 5-1 · 10 6 cells) of cultured retinal capillary pericytes. Because of its efficiency, accuracy and applicability to the separation of inositol phosphates from biological samples, this method may be useful in signal transduction studies in cellular systems.

Interaction of arginine vasopressin and angiotensin II on Ca2+ in vascular smooth muscle cells

The non-osmotic release of arginine vasopressin (AVP) is associated with the concomitant activation of the renin-angiotensin and sympathetic nervous systems. In vivo studies suggest that a positive interaction may occur between AVP and angiotensin II (Ang II), and other Ca2+ mobilizing hormones. In the present study, the cellular mechanisms of this interaction between AVP and Ang II in vascular smooth muscle cell (VSMC) were examined. These results support the existence of a positive interaction between AVP and Ang II on Ca2+ mobilization in VSMC. In fact, the challenge of VSMC with combined AVP and Ang II, in a range from 5 x 10(-11) to 10(-8) M, enhanced cytosolic free Ca2+ ([Ca2+]i) and 45Ca2+ efflux in a more than additive manner. This potentiation, which was not dependent of the presence of extracellular calcium, correlated with an increased VSMC shape change. Moreover, the combination of subthreshold doses of AVP and Ang II (5 x 10(-11) M), which do not release Ca2+ alone, evoked a Ca2+ mobilizing response. A subthreshold dose of Ang II also shifted to the left the concentration-response curve of the AVP-mediated 45Ca2+ efflux. Since there were no changes in receptor binding of either hormone by the other hormone and the interaction of the two hormones on the production of inositol phosphatides was additive, the AVP and AII positive interaction on Ca2+ mobilization on VSMC may occur at the level of the intracellular Ca2(+)-releasing mechanism itself. Such an interaction can occur at hormone concentrations below the Ca2+ release threshold and may explain an increased functional response to the combination of pressor hormones compared to that of each hormone alone.

Role of calcium released from the sarcoplasmic reticulum of smooth muscle cells as induced by inositol phosphatides.

Phosphatidylinositol 4,5-bisphosphate (PI-P2), distributed at the sarcolemma in smooth muscles, as a phospholipid, is hydrolyzed into inositol 1,4,5-trisphosphate (below Ins-1,4,5-P3) and diacylglycerol (DG) by activations of each receptor through actions of GTP binding protein (Gprotein) and by those of phospholipase C. The latter is also synthesized from phosphatidyl inositide monophosphate (Berridge, 1984; Berridge and Irvine, 1984; Abdel-Latif, 1986). It is now clear that Ins-1,4,5-P3 releases Ca from the sarcoplasmic reticulum (SR) of smooth muscle cells and increases free Ca concentration in the cytosol, thereby initiating contraction (Streb et al., 1983; Suematsu et al., 1984; Somlyo et al., 1985; Yamamoto and van Breemen, 1985; Hashimoto et al., 1986; Sasaguri et al., 1985). DG with phosphatidylserine (PS) activates protein kinase C and phosphorylates the proteins required to regulate physiological functions in the cells (Nishizuka, 1984; 1986). In smooth muscles, 12-0-tetradecanoylphorbol-13-acetate (TPA), a phorbol ester and a substitute of DG, together with PS increases the Ca sensitivity of contractile proteins and enhances the mechanical response evoked by high K (below 59 mM) in intact smooth muscles and also by Ca (below 0.5 μM) in skinned muscle tissues (Itoh et al. 1987). TPA also inhibits the hydrolysis of PI-P2 triggered by agonists and reduces the synthesis of Ins-1,4,5-P3 (Itoh et al., 1988).

Molecular species of glycerolipids of Ehrlich ascites cells and of their fat granules.

Ehrlich ascites cells were grown in mice and were isolated by centrifugation of the ascites fluid. The cells were lysed with distilled water, and the floating fat particles were collected by centrifugation. The particles contained about 90% neutral and 10% polar lipid. The neutral lipid was made up of about 50% triacylglycerol, 30% alkyldiacylglycerol, 3% cholesteryl esters, 3% free cholesterol and 4% free diacylglycerols. The phospholipid fraction was comprised of about 50% phosphatidylcholine, 35% phosphatidylethanolamine, 10% sphingomyelin and small amounts (less than 5% total) of serine and/or inositol phosphatides. The triacylglycerol and alkyldiacylglycerol fractions possessed total carbon number and fatty acid compositions closely similar to those reported in the literature for whole ascites cells and for a cell membrane preparation. Likewise, the fatty acid composition of phospholipids from the granules in general was similar to that reported for Ehrlich ascites cells. On the basis of the polar and neutral lipid ratio, the lipid granules of the ascites cells were calculated to possess lipid core diameters of 30-50 nm, which were 40-70 times smaller than those (up to 2 mu) measured for the lipid granules of the intact cells by electron microscopy. The characterization of the lipid composition of the Ehrlich ascites lipid granules was completed by determining the molecular species composition of the diacyl, alkylacyl and alkenylacyl phosphatidylethanolamines and of the diacyl and alkylacyl phosphatidylcholines of the ascites cells. It is concluded that the alkyldiacylglycerols of the Ehrlich ascites cells occur largely in the cytoplasmic lipid granules, which appear to consist of many particles of the size and structure of very low density lipoproteins enclosed in membranous sacs.

The 5-hydroxyl of [formula omitted]-inositol is essential for uptake into HSDM 1C 1 mouse fibrosarcoma cells

We attempted to replace the myo -inositol in cellular inositol phosphatides with 5-deoxy- myo -inositol to evaluate the role of inositol 1,4,5-trisphosphate as a second messenger. This analog, lacking a 5-hydroxyl, might be incorporated into 5-deoxyphosphatidylinositol and converted to the corresponding phosphatidylcyclitol 4-phosphate but could not be converted to phosphatidylinositol 4,5-diphosphate, the precursor of the second messenger molecule inositol 1,4,5-trisphosphate. We synthesized 5-deoxy- myo -inositol and found that this analog does not replace myo -inositol as an essential growth factor for essential fatty acid deficient HSDM 1C 1 mouse fibrosarcoma cells. Furthermore, [5- 3H]-5-deoxy- myo -inositol was neither incorporated into the phospholipids nor accumulated in the cytoplasm of these cells. It appears that this cell line has a specific myo -inositol uptake system that excludes a potentially harmful analog of inositol.

Thyrotropin-releasing hormone rapidly activates protein phosphorylation in GH3 pituitary cells by a lipid-linked, protein kinase C-mediated pathway.

Thyrotropin-releasing hormone (TRH) is a tripeptide that rapidly enhances prolactin secretion in clonal, hormone-responsive GH3 rat pituitary cells. In an effort to identify postreceptor mechanisms for TRH, protein phosphorylation studies have been conducted. Our previous studies (Drust, D.S., Sutton, C.A., and Martin, T. F. J. (1982) J. Biol. Chem. 257, 3306-3312; Drust, D.S., and Martin, T. F. J. (1982) J. Biol. Chem. 257, 7566-7573) showed that TRH rapidly (less than 15 s) increased the phosphorylation of at least six cytosolic proteins (41K (Mr = 41,000), several 59K, 65K, 82K, and 97K) and, with a 5- to 10-min latency, increased the phosphorylation of a seventh (80K). Cyclic AMP did not appear to mediate TRH-stimulation of protein phosphorylation; in contrast, Ca2+ translocation and Ca2+-dependent protein phosphorylation accounted for hormone-induced changes in 97K (and possibly 41K) phosphorylation. The studies reported here indicate that lipid (diacylglycerol) accumulation and protein kinase C activation mediate TRH-stimulated phosphorylation of the additional five cytosolic proteins (two 59K, 65K, 80K, and 82K). This conclusion is based on the findings that: 1) phospholipase C treatment, which produces diacylglycerol, mimicked several TRH effects; 2) bombesin, another peptide that induces inositol phosphatide turnover, mimicked several TRH effects; 3) phorbol esters, which were shown to activate GH3 cell protein kinase C directly, produced TRH-like effects; 4) partially purified GH3 cell cytosolic protein kinase C was activated by diacylglycerol; and 5) 59K and 82K proteins were endogenous in vitro substrates for a cytosolic lipid-stimulated protein kinase. We conclude that rapid TRH effects in promoting inositol phosphatide turnover in GH3 cells may be linked to the activation of protein phosphorylation mediated by protein kinase C. These, and previously reported studies, indicate a role for Ca2+ and lipids (diacylglycerol) as dual intracellular messengers for TRH.

Thyrotropin-releasing hormone rapidly activates the phosphodiester hydrolysis of polyphosphoinositides in GH3 pituitary cells. Evidence for the role of a polyphosphoinositide-specific phospholipase C in hormone action.

The early actions of thyrotropin-releasing hormone (TRH) have been studied in hormone-responsive clonal GH3 rat pituitary cells. Previous studies had demonstrated that TRH promotes a "phosphatidylinositol response" in which increased incorporation of [32P]orthophosphate into phosphatidylinositol and phosphatidic acid was observed within minutes of hormone addition. The studies described here were designed to establish whether increased labeling of phosphatidylinositol and phosphatidic acid resulted from prior hormone-induced breakdown of an inositol phosphatide. GH3 cells were prelabeled with [32P]orthophosphate or myo-[3H]inositol. Addition of TRH resulted in the rapid disappearance of labeled polyphosphoinositides, whereas levels of phosphatidylinositol and other phospholipids remained unchanged. TRH-promoted polyphosphoinositide breakdown was evident by 5 S and maximal by 15 s of hormone treatment. Concomitant appearance of inositol polyphosphates in [3H]inositol-labeled cells was observed. In addition, TRH rapidly stimulated diacylglycerol accumulation in either [3H]arachidonic- or [3H]oleic acid-labeled cultures. These results indicate that TRH rapidly causes activation of a polyphosphoinositide-hydrolyzing phospholipase C-type enzyme. The short latency of this hormone effect suggests a proximal role for polyphosphoinositide breakdown in the sequence of events by which TRH alters pituitary cell function.

Studies on neurotransmitter-stimulated phospholipid metabolism with cerebral tissue suspensions: A possible biochemical correlate of synaptogenesis in normal and undernourished rats

The phenomenon of neurotransmitter-stimulated incorporation of 32Pi into phosphatidic acid and inositol phosphatides (neurotransmitter effect) in developing brain was studied in vitro as a possible measure of synaptogenesis. While the neurotransmitter effect was not observed with brain homogenates, highly consistent and significant effects were noted with brain tissue suspensions obtained by passing the tissue through nylon bolting cloth. The magnitude of the effect decreased with the increase in mesh number. Maximum stimulations obtained with the 33 mesh adult brain cortex preparations (mean±S.E.M. of6experiments) were203 ± 8%, 316 ± 11 % and150 ± 8% with 10 −3 M acetylcholine (ACh) + 10 −3 M eserine; 10 −2 M norepinephrine (NE) and 10 −2 M serotonin (5-HT), respectively. Experiments with developing rat brain at 7, 14 and 21 days of age showed that the neurotransmitter effects due to ACh, NE and 5-HT increase progressively in different regions of the brain but that there are marked regional differences. It is suggested that the neurotransmitter effect is a valid biochemical correlate of synaptogenesis. In rats undernourished from birth t0 21 days of age, by increasing the litter size, the neurotransmitter effect with ACh, NE or 5-HT was not altered in the cortex but was significantly reduced in the brain stem. In cerebellum the effects due to ACh and NE were significantly altered, while that with 5-HT was unaffected. It is concluded that cholinergic, adrenergic and serotonergic synapses are relatively unaffected in the cortex but are significantly affected in the brain stem by undernutrition. In the cerebellum of undernourished rats the adrenergic and cholinergic, but not serotonergic systems, are altered.

Chymotrypsinogen · inositol phosphatide complexes and the transport of digestive enzyme across membranes

Chymotrypsinogen A was almost quantitatively extracted from aqueous solution in the presence of inositol phosphatides at relatively low concentrations of both ligands. Calcium ion facilitated the interaction at concentrations of 10 −4–10 −5 M. A water-insoluble chymotrypsinogen · Ca 2+ · inositol phosphatide complex was formed with an apparent stochiometry of 3 mol phospholipid : 3 mol Ca 2+ : 1 mol protein. Small changes in the structure of the protein prevented complex formation; in particular, the almost identical α-chymotrypsin, did not form complexes under the conditions studied. On the other hand, an homologous, but structurally substantially different, secretory protein, trypsinogen, did form complexes. Water-insoluble complexes were not formed with albumin, carbonic anhydrase or lactic dehydrogenase under the same circumstances. Neither phosphatidylethanolamine nor phosphatidylcholine formed complexes with chymotrypsinogen. Phosphatidylserine formed complexes, but was less effective than inositol phosphatides. Complex formation and stability was dependent upon “critical” concentrations of both Ca 2+ and H +. Extraction of the protein from solution increased from neglible to complete when the calcium concentration of the medium was raised slightly from 1.0 · 10 −4 M to 1.5·10 −4 M. Conversely, dissociation was complete when H + concentration was decreased slightly from pH 6.5 to 7.0. The complex is apparently formed as the result of specific electrostatic interactions between the polar head group of the inositol phosphatide and the protein, with the nonpolar alipathic fatty acid chains of the phospholipid providing a hydrophobic microenvironment for the protein. It is proposed that such complexes could account for the movement of digestive enzyme through membranes.

Distribution of newly formed fatty acids among glycerolipids of isolated perfused rat liver.

Livers of chow fed rats were perfused 1-3 h with buffer, glucose, albumin, and red blood cells, made up in 100 percent D(2)O. Glycerolipids were isolated and the deuterated fatty acids determined by gas chromatography with mass spectrometry on Silar 5 CP. Percentage of replacement by deuterated acids ranged from 1 to 14, of which palmitate was 87 percent. Differences were found in total lipid class and in subcellular distribution of the newly synthesized acids. Microsomes had 37 percent more deuterated acids than the total or floating fat. At 3 h the highest replacement was found in diacylglycerols (17 percent) and free fatty acids (11 percent). Of the palmitate in hepatic choline and ethanolamine phosphatides, 6.9 percent and 4.7 percent, respectively, contained dueterium. The serine and inositol phosphatides had a higher proportion of deuterated palmitate (7.7 percent) than other phosphatides. The data support the hypothesis that palmitate is incorporated into glycerolipids largely via de novo synthesis while stearate enters them by deacylation-acyl transfer replacement.

Activation of fibrinolysis by certain phospholipids

The fibrinolytic activity of plasmin was found to be significantly increased by phosphatidyl serine and inositol phosphatide. Only these two of a wide variety of lipid-related and micelle-forming agents were effective in enhancing fibrinolysis, though calcium, even at low concentrations, prevented the enhancement effect. Plasmin fibrinolytic activity was assessed by decreased turbidity in a fibrin powder suspension. The effect was not due to stabilization of plasmin by phospholipid under the conditions used. At temperatures near 48°C plasmin itself was destroyed by inositol phosphatide more rapidly than normal. This was taken to indicate some direct interaction between the enzyme protein and the phospholipid, rather than between the fibrin substrate and the phospholipid. The fibrin powder suspension assay was easily manipulated to give a range of substrate concentrations. Rates of fibrinolysis determined at several fibrin levels were expressed as a reciprocal plot assuming a normal three-step enzyme mechanism. Kinetic analysis suggested that the phosphatidyl inositol did not affect the first step of the mechanism, i.e. that involving binding of plasmin to fibrin, but increased the rate of one of the subsequent steps.

Calcification of a lysozyme-inositol phosphatide complex in vitro.

SummaryA synthetic basic protein-acidic phospholipid complex was prepared from lysozyme and inositol phosphatides. Suspension of the complex in metastable calcium phosphate solutions resulted in formation of membrane-bound vesicles and apatite nucleation. The results suggest that calcium binding lipoproteins might have a function in calcification.

Non-antigen-antibody precipitin reactions observed with dextran sulfate, DEAE-dextran, antibiotics, proteins, and phospholipids.

Discussion and SummaryA series of precipitin reactions in agarose gel are described which resemble, but are unrelated to antigen-antibody reactions commonly studied by similar methods. This appears to be due to the lack of interference in agarose by sulfate groups present in ordinary agar. The reactions appear to be due to complexes formed between highly negatively charged compounds such as dextran sulfate, heparin, and inositol phosphatide and the highly positively charged polymyxin and aminoglycoside antibiotics, lysozyme, protamine, DEAE-dextran, and presumably beta lipoproteins as well. Unfortunately, the formation of a precipitin band between human serum and dextran sulfate and sensitivity limited to antibiotic concentrations several-fold higher than achieved during antimicrobial therapy, prevents direct adaptation of these methods to a rapid procedure for detecting basic antibiotics in serum. The approach could conceivably be adapted to measurement of basic drugs in urine or to ultrafiltrates of ser...

The "free" lipids of Brucella abortus Bang. Concerning the neutral lipids

Two different strains of Brucella abortus, strain 1119 and strain Scherle II, were grown on solid media; strain 1119 was harvested after approximately 70 h, strain Scherle II was harvested at different ages of the culture up to 72 h. The “free” total lipids were extracted and from these the neutral lipids were prepared and analyzed. The following results were obtained.Strain 1119 contains 4.5% free lipids of bacterial dry weight. Strain Scherle II contains decreasing amounts of free total lipids from approximately 6% to 1.4% as the age of the culture increases.On a weight basis the free total lipids of strain 1119 contain 8.1% neutral lipids. The neutral lipids of strain Scherle II decrease from more than 60% to approximately 24% (of free total lipids) with increasing age of the culture. The amount of phospholipids, however, remains comparatively constant (in relation to the percentage of total lipids) with increasing age of the culture of strain Scherle II. The results indicate that polar lipids other than phospholipids accumulate as the age of the culture increases, but there is no net storage of lipids.The neutral lipids of strain 1119 contain approximately 30% (on a weight basis) of ubiquinone‐50 (corresponding to 1.2 μmoles/g bacterial dry weight). Strain Scherle II also contains ubiquinone‐50, but in amounts demonstrable by thin‐layer chromatography only after an age of 36–38 h. Ubiquinone‐50 has hitherto been found only in a few bacterial species, while most bacterial species contain lower isoprenologs of ubiquinone.The neutral lipids of strain 1119 contain 51% (on a weight basis) of diglycerides, consisting of the 1,3‐ and the 1,2‐isomers. In strain Scherle II only 1,2‐diglycerides were found. The component fatty acids of the diglycerides of strain 1119 consist of approximately 55% (on a weight basis) of C19 cyclopropane acid (lactobacillic acid).The lactobacillic acid/cis‐vaccenic acid ratio is fairly independent of the age of the culture of strain Scherle II.The amount of unesterified fatty acids is lower in strain 1119 (4.9% of the neutral lipids, on a weight basis) than in strain Scherle II (49 or 67%, according to the culture conditions).Both strain 1119 and strain Scherle II contain probably small amounts of triglycerides, monoglycerides and long‐chain hydrocarbons.The possible significance of the results in the classification of Brucella is discussed.

The turnover of myelin in the adult rat

The rate of loss of radioactivity of lipids of brain subcellular fractions was followed for 56 days after injection of adult rats with uniformly labeled [ 14C]glucose. Myelin did not reach its maximum specific activity until 5 days after injection, then showed a slow rate of loss of radioactivity. When the turnover of the lipid components of purified myelin was measured, inositol phosphatide and lecithin were found to have a more active metabolism than the other myelin lipids which include serine phosphatide, sphingomyelin, ethanolamine phosphatide, cerebroside, cerebroside sulfate, and cholesterol. These results which agree with our previous findings indicate that the metabolism of myelin on the outer layers is identical to that laid down early in the life of the animal. Proteolipid protein showed a half-life of about 35 days, thus was one of the more active myelin components. The pattern of metabolism, though on a longer time scale in myelin, is similar to that of the most active brain membrane fraction. These results are discussed in relation to the possible structure of myelin membranes.

On the possibility of lysophosphatide formation during Wallerian degeneration.

Abstract—During an extensive decomposition of phospholipids, at the end of the second week of Wallerian degeneration, the decomposition of glycerophosphatides were studied in detail. In a degenerative process lasting for 2 weeks about one‐third of the choline phosphatides, two‐thirds of the ethanolamine phosphatides, one‐third of the serine phosphatides and one‐quarter of the inositol phosphatides, were destroyed.The amount of lysophosphatidylcholine decreased proportionally to the destruction of choline phosphatide. On the other hand, the amount of lysophosphatides formed from‘kephalin'‐containing fatty aldehyde, during the marked destruction of these phospholipids, remained constant or increased to a small extent and its percentage distribution increased 2 or 3 times compared with other phospholipids. Ethanolamine phosphatides having a high fatty aldehyde content can be regarded as mainly responsible for the relative accumulation of lysophosphatides.